The present invention relates to a process for the catalytic dehydrogenation of hydrocarbons, such as paraffinic hydrocarbons. More dehydrogenation particularly, the present invention concerns an improved process for the dehydrogenation of paraffinic hydrocarbons having from 3 to 6 carbon atoms. The present invention also relates to the catalyst used to carry out the process.
The catalytic dehydrogenation of hydrocarbons has been possible for many years and constitutes an important catalytic process in view of the increasing demand for dehydrogenated products which are of valuable use in various forms, such as gasolines having a high octane number, plastic materials and synthetic rubbers.
Moreover, in view of the increasing production of LPG (liquified petroleum gas), it seems particularly interesting to be able to convert a part of those paraffinic hydrocarbons into dehydrogenated products such as propylene which is of particular interest for the manufacture of plastic materials.
The catalytic dehydrogenation of hydrocarbons is generally carried out in the presence of catalytic compositions containing platinum deposited on a support. The catalytic compositions can also contain other catalytically active metals such as tin or indium and promoters based on alkaline or alkali-earth metals.
Such processes and catalytic compositions have been described e.g. in U.S Pat. Nos. 2,479,209, 2,602,772, 2,930,763, 3,531,543, 3,745,112, 3,892,657, 3,909,451 or still in U.S. Pat. Nos. 4,329,258, 4,363,721 and 4,430,517.
Further, in most of these patents, it is also taught to use a halogen in order to improve the yield of the dehydrogenation reaction.
However, when the developed processes are applied to the dehydrogenation of propane, the yield of the reaction at 600.degree. C. does not exceed about 30 to 35%. This amount is 70 to 81% of the total theoretical conversion, taking into account the thermodynamic constraints.
There is, therefore, a need to provide a process for the dehydrogenation of paraffinic hydrocarbons with improved yields.